Nitrous oxide, which was discovered by Priestly in 1772, was found to have utility as an anesthetic by Davey in 1800. There are at least two conventional commercial methods for its production. By one method, nitrous oxide is produced catalytically from ammonia and air using pelletized Mn and Bi oxides as catalysts, reportedly with an 85 percent conversion of ammonia per single pass at 310.degree.-350.degree. C. This method is disclosed in a Japanese technical publication entitled "SYNTHESIS OF NITROUS OXIDE BY OXIDATION OF AMMONIA," by T. Suwa, A. Matsushima, Y. Suziki and Y. Namina in Kohyo Kagaku Zasshi, Vol. 64, pp 1879-1888, 1961 and also in Czech. Patent CS No. 186,313, `issued Nov. 30, 1973 to J. Mikoda, see Chem. Abstract 95(22); 189,494a. The feed gas composition used in this patent was calculated to contain about 2 percent ammonia in 98 percent air and the exit gas concentration of nitrous oxide was about 1 percent. On this basis, the nitrous oxide produced must be separated from a much larger volume of air, resulting in relatively high separation costs. In addition, this catalytic method for producing nitrous oxide from ammonia produces several by-product nitrogen compounds, such as nitric oxide and nitrogen dioxide which necessitate additional separation steps.
The second conventional commercial method for the production of nitrous oxide involves the thermal decomposition of ammonium nitrate at about 170.degree. C. according to the equation below: EQU NH.sub.4 NO.sub.3 .fwdarw.N.sub.2 O+2H.sub.2 O.
This method is described in Kirk-Othmer's Encyclopedia of Chemical Technology, Volume 2, p. 527, (1978). Since ammonium nitrate is considered to be a high explosive, precautions must be taken to minimize the risk of explosion when using this production method, including feeding a concentrated aqueous solution of ammonium nitrate into a reactor at 275.degree. C. However, any dry, molten ammonium nitrate in the system that becomes heated above 250.degree. C. poses a detonation risk according to the equation: EQU NH.sub.4 NO.sub.3 .fwdarw.N.sub.2 +1/2O.sub.2 +2H.sub.2 O.
Besides the above two commercial methods for making nitrous oxide, various laboratory methods have also been disclosed. For example, molten nitrate salts have been reported to react with ammonium chloride to produce nitrous oxide, chloride ion, and water according to the equation below: EQU NH.sub.4 Cl+NO.sub.3.sup.- .fwdarw.Cl.sup.- +2H.sub.2 O+N.sub.2 O.
Such a reaction is reported in a technical publication by H. Fouzanfar and D. H. Kerridge in J. Inorg. Nucl. Chem., Vol. 40, pp 1327-1330. This reaction leaves a chloride ion residue in the melt and, with extensive reaction over time, the chloride can build up and actually convert the nitrate melt into a chloride melt. Moreover, the presence of chloride ion can lead to well-known corrosion problems with stainless steels and other conventional materials of reactor construction.
On the basis of the above, an inexpensive, safe method for producing nitrous oxide would be highly desirable. Heretofore, such an inexpensive and safe method involving the use of molten nitrate salts has not been known or suggested to the knowledge of the present inventor.